1. Field of the Invention
The present invention relates to a pixel structure and a display panel having the same, and particularly to a pixel structure and a display panel having the same using polymer stabilized alignment (PSA) technique.
2. Description of Related Art
In the development of the display, with the progress in the optoelectronic techniques and the semiconductor manufacturing techniques, the liquid crystal display with the advantages of high definition, optimal space utilization, low power consumption, and no radiation has gradually become the main stream of the market.
A liquid crystal display includes a backlight module and a liquid crystal display panel, and a conventional liquid crystal display panel is composed by two substrates and a liquid crystal layer between the two substrates. Generally speaking, when the liquid crystal panel is manufactured, alignment films will be formed on the two substrates, such that liquid crystal molecules are aligned in a specific manner. A conventional method of forming the alignment films is coating an alignment material first, and then performing an alignment process on the alignment material. The alignment process can be classified into a contact alignment process and a non-contact alignment process. Though the non-contact alignment process solves the problems of electrostatics and particle contamination in the contact friction alignment, it often leads to the problem of insufficient anchoring energy on alignment surfaces. Insufficient anchoring energy of an alignment surface may result in bad display quality of the LCD panel.
In order to solve the above problems, a polymer stabilized alignment (PSA) technology has been developed. According to this technology, high molecular monomers of an appropriate concentration are doped into the liquid crystal material and are vibrated to an even state. Next, the mixed liquid crystal material is heated to an isotropy state on a heater. Then, when the liquid crystal mixture is cooled to the ambient temperature of 25° C., the liquid crystal mixture returns to a nematic state. At this time, the liquid crystal mixture is injected into the liquid crystal cell, and a voltage is applied thereon. When the arrangement of the liquid crystal molecules is stabilized, the high molecular monomers are bonded to form a polymer layer by means of UV curing or heating, so as to realize the stabilized alignment
Generally speaking, in the PSA LCD panel, alignment slits are formed in the pixel electrode of a pixel structure, so as to allow liquid crystal molecules to have specific alignment directions. The alignment of the liquid crystal molecules is more accurate if more of the alignment slits are formed in the pixel electrode. Since the alignment slits may have non-identical widths due to the photolithography process, more display mura may be generated when the alignment slits occupy more areas of the pixel electrode. For details, in the photolithography process of the alignment slits, the exposing condition at an interface region between optical devices of an exposure apparatus is different from the exposing condition at a non-interface region, and thereby the slits formed in the interface region may have a width different from that of the slits formed in the non-interface region. Therefore, the brightness of these two regions is different and display mura is generated on the display panel.